Let me fill in with my perspective as a Mac user: I expect the vendor (i.e Apple) to supply a decent desktop environment. The did a quite good job at it. I didn’t need to pay extra, it was included in the sale of the computer.

But X.org isn’t a hardware vendor. It’s not owned by any hardware vendor. It’s not even owned by an OS vendor, or by an OS at all.

Apple is a multi-trillion dollar company. Microsoft and Google are close behind. Of course they can give away their desktop environment away for free. System76 (et al) can’t compete with that. X.org can’t compete with that.

I mean, this is exactly the reason I use Mac, because it ships with a good DE out of the box supported by a trillion dollar vendor. But that doesn’t help people who prefer Linux.

It's worth noting that when Apple first developed the (early versions of the) current desktop environment, they were not just not a trillion-dollar company, they were still considered to be "doomed" and on their way out by a large percentage of those who paid any attention to them.